The long-term goal of this project is to understand the molecular mechanisms that cause an increase in protein misfolding and aggregation with age. This is in line with the broad goal of the aging field to identify senescence factors, the specific mechanisms that induce the decline in function associated with age. The hope is that identification of such factors will lead to targeted therapies that slow or reverse the aging process. In this project, we specifically focus on age-induced attenuation of the cellular pathways responsible for preventing and responding to protein misfolding. The malfunction of these pathways appears to be a highly conserved aging phenotype associated with human aging and neurodegeneration, but the specific mechanisms behind the loss of function remain to be elucidated. Taking advantage of conservation of both age-induced protein aggregation and the general mechanisms for responding to folding stress, we use replicative aging of budding yeast as a model for cellular aging and senescence. We have observed that a key regulator of the response to protein folding stress, the Heat Shock transcription factor (Hsf), is inhibited wit age. A genetic screen for suppressor mutations reveled mutants associated with inhibition of a separate stress pathway, the general stress response (GSR), which we later found becomes constitutively active with age. We used a chemical genetics strategy to demonstrate that activity of the GSR is sufficient to suppress Hsf. We will use genetic and biochemical methods to understand the how Hsf is inhibited and how the GSR becomes disregulated with replicative age. Since Hsf is conserved through humans and its malfunction is implicated in human neurodegeneration, elucidation of the mechanisms of age-induced Hsf suppression holds clinical significance. Additionally, we seek to understand how variation in stress pathway function relates to variability of lifespan. Further, we will explore the ability of engineered variation, leading to increased protein folding capacity, can prevent the age-induced accumulation of protein aggregates and extend lifespan.